Multi-speed planetary vehicle transmission

This application is a National Stage completion of PCT/EP20131050356 filed Jan. 10, 2013, which claims priority from German patent application serial no. 10 2012 203 068.9 filed Feb. 29, 2012.

The present invention concerns a multi-gear planetary transmission for a Vehicle.

For example from the document DE 10 2007 055 808 A1 an automatic transmission of planetary design is known, which comprises four planetary gearsets and six shifting elements as well as eight rotating shafts. All the planetary gearsets are in the form of minus planetary gearsets. With the total of six shifting elements ten forward gears and two reverse gears can be engaged selectively. However, from the shifting scheme of the known automatic transmission it can be seen that to produce each gear step, in each case only three of the shifting elements provided are closed. Because of the disk shifting elements that remain open, there are therefore undesirably high drag losses.

The purpose of the present invention is to propose a planetary transmission of the type described to begin with, which is structurally simple, which can be produced as compactly and inexpensively as possible and in which drag losses are also lower.

According to the invention this objective is achieved by the characteristics described below.

A multi-gear planetary transmission is proposed, for example an automatic or automated transmission for a vehicle, which comprises four planetary gearsets or planetary gearset planes and six shifting elements for producing a plurality of gear steps. In this case at least one of the planetary gearsets is designed as a plus planetary gearset, while a shaft constituting the drive input shaft connects the planetary carrier of the first planetary gearset to a third shifting element and a shaft constituting the drive output shaft is coupled at least to the plus planetary gearset, in that the second shaft is connected to the ring gear of the plus planetary gearset, in such manner that in each gear at least four of the six shifting elements are actuated or closed.

In this way, drag losses in the planetary transmission according to the invention are minimized because of the small number of open shifting elements in the engaged condition. It is possible for one or more minus planetary gearsets to be changed to further plus planetary gearsets if at the same time the web or planetary gearwheel carrier connection and the ring gear connection are exchanged and the value of the fixed transmission ratio of the planetary gearset concerned is increased by 1 and provided that the connections of the elements of the planetary gearset so permit. As is known, a minus planetary gearset has planetary gearwheels mounted to rotate on the planetary carrier, which mesh with the sun gear and with the ring gear of the planetary gearset so that when the planetary carrier is fixed and the sun gear is rotating, the ring gear rotates in the opposite direction to the rotational direction of the sun gear. As is also known a plus planetary gearset has, mounted to rotate on its planetary carrier, inner and outer gearwheels which mesh with one another, the sun gear of the planetary gearset meshing with the inner planetary gearwheels and the ring gear of the planetary gearset meshing with the outer planetary gearwheels, so that when the planetary carrier is fixed and the sun gear is rotating, the ring gear rotates in the same direction as the sun gear.

Preferably, in the proposed planetary transmission the drive input shaft and the drive output shaft can be arranged coaxially so as to produce a standard drive input in a vehicle. However, it is also possible to produce a front transverse configuration with the planetary transmission in a vehicle, if the geometrical arrangement and hence the sequence of the elements of the planetary transmission, as for example the arrangement of the individual planetary gearsets and shifting elements is changed, provided that the connections of the transmission elements allow this, in such manner that then, for example, the drive input shaft and the drive output shaft are arranged offset relative to one another.

With the planetary transmission according to the invention a hydrodynamic torque converter or a hydrodynamic clutch can be used as the starting element. It is also conceivable to use an additional starting clutch or an integrated starting clutch or starting brake. Furthermore, additional electric machines can be used. For example, an electric machine or some other source of force and power can be arranged on at least one of the shafts. It is also conceivable to arrange on at least one shaft a freewheel to the housing or else to another shaft. As shifting elements both frictional and interlocking shifting elements can be considered. Preferably, the second shifting element in the form of a brake and the sixth shifting element in the form of a clutch can each be made as claw shifting elements.

In the planetary transmission according to the invention, at least one of the planetary gearsets, for example the third planetary gearset, can be internally locked if two elements of the third planetary gearset are connected by an associated shifting element, for example the fifth shifting element. Thus, the various possible arrangements of the shifting elements provide various locking variants. For example, the ring gear of the third planetary gearset can be connected by way of a fifth shaft and by way of the fifth shifting element to the sun gear in order to lock the planetary gearset. Moreover, the planetary gearwheel carrier of the third planetary gearset can be connected by way of the fifth shifting element and the seventh shaft to the sun gear thereof in order to lock the planetary gearset. Furthermore, the planetary carrier of the third planetary gearset can be connected to the ring gear thereof by way of the eighth shaft, the fifth shifting element and the fifth shaft, with the same locking effect.

In a related further development of the invention, in the planetary transmission proposed it is also possible to implement various functionally equivalent arrangement variations related to a shifting element associated with the third planetary gearset, for example the fourth shifting element which is in the form of a clutch. For one thing, the fourth shifting element can be positioned on the web or planetary carrier of the third planetary gearset. The fourth shifting element can also be arranged on the ring gear or even on the sun gear of the third planetary gearset. From the resulting, functionally equivalent alternatives, various design arrangements of the gearset of the planetary transmission according to the invention can be produced, for example in order to enable adaptation of the planetary transmission to a predetermined fitting space.

Below, the present invention is explained in more detail with reference to the drawings, which show:

FIG. 1 : A schematic view of a first embodiment variant of a planetary transmission according to the invention;

FIG. 2 : A shifting scheme for the planetary transmission according to the invention;

FIG. 3 : A schematic view of a second embodiment variant of the planetary transmission according to the invention, with a variant for locking the third planetary gearset;

FIG. 4 : A schematic view of a third embodiment variant of the planetary transmission according to the invention, with a further variant for locking the third planetary gearset;

FIG. 5 : A schematic view of a fourth embodiment variant of the planetary transmission according to the invention, with a different arrangement of shifting elements; and

FIG. 6 : A schematic view of a fifth embodiment variant of the planetary transmission according to the invention, with another different arrangement of shifting elements.

The figures represent various embodiment variants of the planetary transmission according to the invention, used for example as an automatic or automated transmission for a vehicle.

Regardless of the particular embodiment variant, the planetary transmission comprises four planetary gearsets RS 1 , RS 2 RS 3 , RS 4 and six shifting elements A, B, C, D, E, F as well as nine shafts I, II, III, IV, V, VI, VII, VIII, IX, wherein the term ‘shaft’ is understood to mean one or more components of any structural form which connect or couple at least two elements of the planetary transmission. In the planetary transmission according to the invention the required housing couplings are produced by means of shifting elements in the form of brakes, so there are no fixed housing couplings.

The planetary gearsets used are minus planetary gearsets and plus planetary gearsets, and in the embodiment variants shown the first three planetary gearsets RS 1 , RS 2 , RS 3 are each minus planetary gearsets and the fourth planetary gearset RS 4 is a plus planetary gearset.

Regardless of the particular embodiment variant, the first shifting element A and the second shifting element B are brakes, in order to produce shiftable housing couplings. The third shifting element C, the fourth shifting element D, the fifth shifting element E and the sixth shifting element F are in each case clutches.

In the first embodiment variant of the planetary transmission according to the invention shown in FIG. 1 the first shaft I, which is the drive input shaft An of the transmission, is connected to the planetary carrier PT 1 of the first planetary gearset RS 1 and to a third shifting element C in the form of a disk clutch. The second shaft II, which is the drive output shaft Ab of the transmission, is connected to a ring gear HO 4 of the fourth planetary gearset RS 4 and to a fourth shifting element D also in the form of a disk clutch. To form the first shiftable housing coupling a third shaft III is provided, by which the ring gear HO 2 of the second planetary gearset RS 2 is connected to the first shifting element A in the form of a disk brake, so that when the first shifting element A is closed the ring gear HO 2 is connected to the housing G. A fourth shaft IV forms the second shiftable housing coupling, in which the sun gear SO 4 of the fourth planetary gearset RS 4 is connected by the fourth shaft IV to the second shifting element B in the form of a disk brake so that when the shifting element B is closed the sun gear SO 4 is connected to the housing. A fifth shaft V connects the ring gear HO 3 of the third planetary gearset RS 3 both to the fifth shifting element E and also to the sixth shifting element F, each of them in the form of disk clutches. A sixth shaft VI connects the ring gear HO 1 of the first planetary gearset RS to the planetary carrier PT 2 of the second planetary gearset RS 2 and to the planetary carrier PT 4 of the fourth planetary gearset RS 4 , so that the planetary carrier PT 4 of the fourth planetary gearset RS 4 forms the mounting both for the inner planetary gearwheels PRI 4 which mesh with the sun gear SO 4 and also for the outer planetary gearwheels PRA 4 . The outer planetary gearwheels PRA 4 mesh both with the inner planetary gearwheels PRI 4 and with the ring gear HO 4 . A seventh shaft VII connects the sun gear SO 1 of the first planetary gearset RS 1 to the fifth shifting element E and to the sun gear SO 3 of the third planetary gearset RS 3 . By means of an eighth shaft VIII a connection is formed between the fourth shifting element D and the planetary carrier PT 3 of the third planetary gearset RS 3 . A ninth shaft IX connects the third shifting element C to the sun gear SO 2 of the second planetary gearset RS 2 and to the sixth shifting element F.

Starting from this first embodiment variant according to FIG. 1 , FIG. 3 shows a second embodiment variant in which an alternative option for locking the third planetary gearset RS 3 is illustrated. In this second embodiment variant, by contrast with the first embodiment variant the locking is effected in that the planetary carrier PT 3 can be connected by way of the fifth shifting element E and by way of the seventh shaft VII to the sun gear SO 3 of the third planetary gearset RS 3 .

FIG. 4 shows a third embodiment variant of the planetary transmission according to the invention, in which another locking variant of the third planetary gearset RS 3 is illustrated. In this third embodiment variant, by contrast with the first and second embodiment variants, the locking is effected in that the planetary carrier PT 3 can be connected to the ring gear HO 3 of the third planetary gearset RS 3 by way of the eighth shaft VIII and by way of the fifth shifting element E as well as by the fifth shaft V.

FIGS. 5 and 6 show fourth and fifth embodiment variants of the planetary transmission according to the invention in which, compared with the first embodiment variant, different arrangements of the fourth shifting element D are shown. These embodiment variants are functionally equivalent to the first embodiment variant.

To be specific, in the fourth embodiment variant according to FIG. 5 the first shaft I, which is the drive input shaft An, is connected to the planetary carrier PT 1 of the first planetary gearset RS 1 and to the third shifting element C, whereas the second shaft II, which is the drive output shaft Ab, is connected to the planetary carrier PT 3 of the third planetary gearset RS 3 and to the ring gear HO 4 of the fourth planetary gearset RS 4 . The ring gear HO 2 of the second planetary gearset RS 2 can be connected fixed to the housing by the third shaft III and by way of the first shifting element A. The fourth shaft IV can connect the sun gear SO 4 of the fourth planetary gearset RS 4 fixed to the housing when the second shifting element B is closed. The ring gear HO 3 of the third planetary gearset RS 3 is connected to the fourth shifting element D by the fifth shaft V. The sixth shaft VI connects the ring gear HO 1 of the first planetary gearset RS 1 to the planetary carrier PT 2 of the second planetary gearset RS 2 and to the planetary carrier PT 4 of the fourth planetary gearset RS 4 . The seventh shaft VII connects the sun gear SO 1 of the first planetary gearset RS 1 to the sun gear SO 3 of the third planetary gearset RS 3 and to the fifth shifting element E. Finally, the ninth shaft I connects the sixth shifting element F to the sun gear SO 2 of the second planetary gearset RS 2 and to the third shifting element C.

In the fifth embodiment variant according to FIG. 6 , to be specific, the first shaft I which is the drive input shaft An of the transmission is connected to the planetary carrier PT 1 of the first planetary gearset RS 1 and to the third shifting element C. The second shaft II, which is the drive output shaft Ab of the transmission, connects the planetary carrier PT 3 of the third planetary gearset RS 3 to the ring gear HO 4 of the fourth planetary gearset RS 4 . The third shaft III connects the ring gear HO 2 of the second planetary gearset RS 2 to the housing when the first shifting element A is closed. By way of the fourth shaft IV the sun gear SO 4 of the fourth planetary gearset RS 4 can be connected to the housing G by means of the second shifting element B. By means of the fifth shaft V the ring gear HO 3 of the third planetary gearset RS 3 is connected to the fifth shifting element E and to the sixth shifting element F. The sixth shaft VI connects the ring gear HO 1 of the first planetary gearset RS 1 to the planetary carrier PT 2 of the second planetary gearset RS 2 and also to the planetary carrier PT 4 of the fourth planetary gearset RS 4 . By the seventh shaft VII the sun gear SO 1 of the first planetary gearset RS 1 is connected to the fourth shifting element D and to the fifth shifting element E, while the eighth shaft VIII connects the sun gear SO 3 of the third planetary gearset RS 3 to the fourth shifting element D. Finally, the ninth shaft IX connects the sixth shifting element F to the sun gear SO 2 of the second planetary gearset RS 2 and to the third shifting element C.

In the shifting scheme shown in FIG. 2 , the shifting elements A, B, C, D, E, F to be closed or activated in order to produce the various gears are represented in the form of a table, and for each gear a transmission ratio i and the respective gear intervals φ between various gears are indicated. Besides the nine forward gears 1, 2, 3, 4, 5, 6, 7, 8, 9 and the one reverse gear R indicated, four additional or alternative gears for the planetary transmission are shown, these being denoted by M. Preferably, the first two gears denoted by M are used as alternative fourth forward gears and the last two gears denoted by M are used as alternative first forward gears.

As the preferred fixed transmission ratio, for the first planetary gearset RS 1 a value of approximately i 0 =−1.600 can be used, for the second planetary gearset RS 2 a value of around i 0 =−1.500, for the third planetary gearset RS 3 a value of around i 0 =−3.200 and for the fourth planetary gearset RS 4 a value of around i 0 =2.200 can be used.

The various embodiment variants of the planetary transmission claimed according to the invention are characterized by particularly little structural complexity, low production costs and low weight. Furthermore, the proposed shifting scheme provides a harmonious series of transmission ratios with low absolute and relative rotation speeds and low planetary gearset and shifting element torques. Moreover, thanks to the connections chosen between the various elements of the proposed planetary transmission the gearing efficiencies are substantially optimized. In addition, since for each gear at least four disk shifting elements are closed, drag losses are low.

1 First forward gear

2 Second forward gear

3 Third forward gear

4 Fourth forward gear

5 Fifth forward gear

6 Sixth forward gear

7 Seventh forward gear

8 Eighth forward gear

9 Ninth forward gear

R Reverse gear

M Alternative or additional gears

G Housing

RS 1 First planetary gearset

PT 1 Planetary carrier of the first planetary gearset

HO 1 Ring gear of the first planetary gearset

SO 1 Sun gear of the first planetary gearset

RS 2 Second planetary gearset

PT 2 Planetary carrier of the second planetary gearset

HO 2 Ring gear of the second planetary gearset

SO 2 Sun gear of the second planetary gearset

RS 3 Third planetary gearset

PT 3 Planetary carrier of the third planetary gearset

HO 3 Ring gear of the third planetary gearset

SO 3 Sun gear of the third planetary gearset

RS 4 Fourth planetary gearset

PT 4 Planetary carrier of the fourth planetary gearset

HO 4 Ring gear of the forth planetary gearset

SO 4 Sun gear of the fourth planetary gearset

PRI 4 Inner planetary gearwheels of the fourth planetary gearset

PRA 4 Outer planetary gearwheels of the fourth planetary gearset

I First shaft

II Second shaft

III Third shaft

IV Fourth shaft

V Fifth shaft

VI Sixth shaft

VII Seventh shaft

VIII Eighth shaft

IX Ninth shaft

An Drive input

Ab Drive output

A First shifting element

B Second shifting element

C Third shifting element

D Fourth shifting element

E Fifth shifting element

F Sixth shifting element